Motor control system



W. 0. LUM.

MOTOR CON'KRGL SYSTEM.

.fill Luba?? CIK the resistor 2l,

127, or the weight incense the coil 5l will be broken by the arm lo,nihil the switch will be controlled by the coil 8 only. I

A modication of my invention is illustrated in Fig. 2 in which similarnumerals are employed to designate corresponding parts. ln themodification, the rate ot' acceleration is controlled by aa resistor 2lthat is in series with the armature 4 of the motor. Normally, whenthemotor 3 is being accelerated atits normal rate, the switch "l", whichis normally closed to short circuit is controlled by theJ coil 8 alone.llt the rate of accelention fall' below the normal Value, the arm l5 ofthe accelerometerwill operate to close the circuit of the coil 9, in themanner described above. in connection with lF l, and the coil 9 will beenergized to oppose the action of the coil 8. The switch 7 will thenremain closed until the current hes reached a higher predetermined valuethan when actuated by the coil 8 only. The' result is to allow thearmature 4f to receive current at a. higher Y:ilus without opening `theswitch 7 and thereby increase the rate of acceleration of th@ motor. Theoperation ot the system illustrated in Fig. 2 differs in no other mate`rial resjectl from that ot' Fig'. l.

.it will he noted that l have provided a simple and effective means forcontrolling the rate of acceleration of an electric motor in accordancewith the demands of the load.

lt will be understood, also, that the values at which the current-limitswitch 7 is ranged to operate7 may he varied, as desired., byadjlistingl the coils 8 and 9 and by adjusting the strength oit thcsprings lf3 and and length of the erm l5 of the device l0.

l. claim as my invention:

l.. In a motor-control system, the combination with assure@ of currentand au electric motor having; a shunt held winding, of means controlledhy the rate of acceleration ol'l said motor for' controllinirr theexcitation of said lield winding.

2. ln a motoncontrol system, the combination with a source of current,and an electric motor, or an elceti-omaguetic switch having a pluralityoi'.j actuating coils for controlling' the circuit conditions olf seidmotor, said switch being arranged to op* crate at a. predeterminedcurrent Value, and means controlled by the .rate of ecceleration of saidmotor for, controlling` the circuit ot on@j of said coils.

ln a motorcontrol the combisystem,

nation with a source of current and an electric motor, of a switchhaving` a plurality of actuating coils, one of said vcoils being` incircuit withl said motor, and means controlled by the rate ofacceleration said motor for controlling the Connections of another oiseid actuating` coils.

ln a motor-control system, the combination with a source of current andan electric motor, ot means for automatically controlling the rate ofacceleration of said motor, said. means comprising an electromagneticswitch having actuating coils that are wound to oppose each other andarranged to operate at a predetermined current value, and meanscontrolled by the rate of acceleration. of said motor tor controllingthe circuit of one of said coils and there-by causing; said switch tooperate at a second predetermined value.

5. In a motor-control,system, the combination with a source of currentand an. electric motor, of a resistor in circuit with said motor, andmeans for automatically controlling; said resistor, said meanscoinivnising an electromagnetic switch having a plurality of actuatingcoils and means controlled hy the ate of acceleration of said motor 'forconi trolling the circuit of one of said coils.

G. ln a motor control system, the combination with a source of currentand an electric motor having a shunt iield winding, of a resistor incircuit with seid field Winding, an electromagnetic switch Vforcontrolling said resistor, said switch being adapted to operate when thecurrent'in the mot-or circuit rcaches a predetermined value, and meanscomprisingl chanically connected to said motor 'for varying` saidpredetermined Value.

.7. ln a motor control system,y the combination with a source oi'current, and 'i electric motor, olf resistor in circuit with said motor,and means for automatically control ling,y said resistor, said meanscomprising; an electromagnetic switch l'iavingg` a plurality ofactuating; coils circuit of one of said coils when the rate ofacceleration of said motor reaches a. prede termiued minimum `value.

in testimony whereof, l subscribed my name this 13th 19M.

have hereui'ito day or lllarclf,

il?. Corinna ero u, l. l.' linens.

and means forffclosinu the l lil

